BigShinyThing

The investigation was prompted the case of a dog alerting its owner to the presence of a melanoma by constantly sniffing the skin lesion. Subsequent studies published in major medical journals further confirmed the ability of trained dogs to detect both melanomas and bladder cancers — as reported by the BBC earlier this year. This new study, led by Michael McCulloch of the Pine Street Foundation in San Anselmo, California, and Tadeusz Jezierski of the Polish Academy of Sciences, Institute of Genetics and Animal Breeding, is the first to test whether dogs can detect cancers only by sniffing the exhaled breath of cancer patients.

Five household dogs were trained over a three week period to detect lung or breast cancer by sniffing the breath of cancer participants. The trial itself was comprised of 86 cancer patients — 55 with lung cancer and 31 with breast cancer — and a control sample of 83 healthy patients. All the cancer patients had recently been diagnosed and had not yet undergone any chemotherapy. The dogs were presented with breath samples from the cancer patients and the controls, captured in a special tube. Dogs were trained to give a positive identification of a cancer patient by sitting or lying down directly in front of a test station containing a cancer patient sample, while ignoring the control samples.

The results were astonishing: the dogs detected breast and lung cancer with a sensitivity and specificity between 88% and 97%. The high accuracy persisted even after results were adjusted to take into account whether the lung cancer patients were currently smokers. Moreover, the study also confirmed that the trained dogs could even detect the early stages of lung cancer, as well as early breast cancer.